Surgical access device with floating gel seal

ABSTRACT

A trocar is provided with a cannula and a housing and valve assembly disposed in the housing which forms a housing seal, and instrument seal, and in some cases a zero seal. A gel material is included in the valve and provides the valve with superior flotation properties for maintaining the instrument seal even when the instrument is moved off-axis. In order to accommodate movement of the gel material, voids can be formed within the valve housing and even within the gel material.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.12/693,860, filed Jan. 26, 2010, which is a continuation of U.S.application Ser. No. 11/753,752, filed May 25, 2007, now U.S. Pat. No.7,651,478, which is a continuation of U.S. application Ser. No.10/056,831, filed Jan. 24, 2002, now U.S. Pat. No. 7,235,062, all thedisclosures of which are incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to surgical access devices and morespecifically to valves and seals associated with such devices.

2. Discussion of the Related Art

Access devices are commonly used to facilitate the introduction ofsurgical instruments into body conduits and body cavities. One suchdevice, which is typically referred to as a trocar, is used inlaparoscopic procedures to provide access through the abdominal wall andinto the abdominal cavity. In laparoscopic surgeries, the abdominalcavity is commonly inflated or insufflated in order to increase thevolume of the working environment. Under these circumstances, valves areprovided in a valve housing of the trocar to inhibit the escape of theinsufflation gas. The valves form an instrument seal in the presence ofan instrument, and a zero seal in the absence of an instrument.

Trocar seals are disclosed and claimed in applicant's U.S. Pat. No.5,385,553, which is incorporated herein by reference. This patentdiscusses the problems which can be encountered when the instrument isinserted off-axis. The solution of floating the valve is discussed indetail.

In this patent it is contemplated that the valve would comprise firstportions which define an orifice through the valve and second portionsdisposed outwardly of the first portions. These second portions areintended to provide a greater flexibility than the first portions. As aconsequence, when an instrument is inserted off-axis, the secondportions will deform while the first portions, which form the instrumentseal, will remain undeformed. One of the embodiments contemplatesprovision of an excess of material disposed outwardly of the valveorifice which functions generally as a bellows. In this case the firstportions of the valve have a first radial length to radial distanceratio while the second portions of the valve have a second radial lengthto radial distance ratio. The valving mechanism is formed generally of asolid but elastomeric material.

SUMMARY OF THE INVENTION

In accordance with the present invention, an access device is provided,for example, in the form of a trocar having a valve housing. In thiscase, a valve assembly is disposed in the housing and includes a gelmaterial which has superior sealing characteristics and flotationproperties. In some respects, the gel is a solid in that it has agenerally fixed volume. On the other hand, the gel functions somewhatlike a liquid in that it tends to “flow.” Other characteristics of thegel material, such as an elongation greater than 1000 percent, a lowdurometer and an excellent tear strength are disclosed and claimed inapplicant's International Application No. PCT/US01/29682. Thisapplication, which was filed on Sep. 21, 2001 and entitled “SurgicalAccess Apparatus and Method”, is incorporated herein by reference.

The gel material will typically form a seal with the valve housing andmay also be used to form the instrument seal as well as the zero seal.Alternatively, the valve assembly can be formed with a typical septumvalve supported by the gel material to provide the septum valve with thesuperior flotation properties.

In order to facilitate compression of the gel material, voids can becreated in the housing or even within the gel material to accommodatecompression of the material during insertion of an instrument.

Aspects of the Invention

In one aspect of the invention, a trocar has an axis and is adapted toprovide access for a surgical instrument across a body wall and into abody cavity. A cannula, disposed along the axis, has a proximal end anda distal end, and is adapted for disposition across the body wall. Ahousing disposed along the access at the proximal end of the cannula isadapted to receive the surgical instrument and to introduce theinstrument into the cannula. A valve is disposed in the housing andprovided with properties for forming a first seal with the housing wall,a second seal with the instrument when it is present in the trocar and athird seal with itself when the instrument is absent from the trocar. Agel material included in the valve has flotation properties formaintaining the second seal even when the surgical instrument is movedlaterally of the axis of the trocar.

In another aspect of the invention, a valve assembly includes a septumvalve disposed in the valve housing and adapted to form a first sealwith the instrument when it is received into the trocar. A valve supportis disposed between the septum valve and the housing to float the septumvalve relative to the housing. The valve support includes a gel havingelongation greater than 1000 percent to facilitate maintenance of thefirst seal during off-axis movement of the instrument relative to thehousing. The septum valve can be insert molded to the valve support. Inanother aspect of the invention, a valve is disposed in the valvehousing and adapted to form a seal with the instrument when theinstrument is inserted through the valve housing and into the cannula.Portions of the valve include a gel material having properties formoving relative to the axis to maintain the seal with the instrumentwhen the instrument is moved off-axis.

Voids can be formed in proximity to the gel material to facilitatemovement of the material relative to the axis. These voids can be formedprimarily on the walls of the valve housing, between the walls and thegel material and even within the gel material.

These and other features and advantages of the invention will becomemore apparent with a description of preferred embodiments in referenceto the associated drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a patent operatively position with atrocar extending into the abdominal cavity and providing access for asurgical instrument;

FIG. 2A is an axial cross section view of one embodiment of the trocar,and illustrates a zero seal configuration in the absence of theinstrument;

FIG. 2B is a cross section view taken along lines IIB-IIB of FIG. 2A;

FIG. 3 is an axial cross section view of the trocar illustrating aninstrument seal formed during off-axis insertion of the instrument;

FIG. 4 is an axial cross section view of another embodiment of theinvention including a septum seal and a floating gel support;

FIG. 5 is an axial cross section view of another embodiment of the valveapparatus;

FIG. 6 is an axial cross section view of a valve apparatus with gelmaterial including air pockets; and

FIG. 7 is an axial cross section view of a further embodimentillustrating air pockets formed in the seal housing.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS AND BEST MODE OF THEINVENTION

A patient is illustrated in FIG. 1 and designated generally by thereference numeral 10. The patient 10 is illustrated in a prone positionon an operation table 12 where he is prepared for laparoscopic surgery.This type of surgery is performed within the patient's abdominal cavity14 with minimal access through an abdominal wall 16. This access istypically provided by a trocar 18 having a cannula 21 and valve housing23. The trocar 18 may be one of several trocars which are usedsimultaneously to provide access for surgical instruments such as theinstrument 25 illustrates in the form of a laparoscope.

During a laparoscopic procedure the abdomen 14 is typically inflatedwith an insufflation gas, such as carbon dioxide, in order to distendthe abdominal wall 16 and thereby increase the volume of the workingenvironment. It is the purpose of the valve housing 23 and associatedvalves to maintain this insufflation gas within the abdominal cavity 14,both in the presence of the instrument 25 and in the absence of theinstrument 25.

One embodiment of the trocar 18 of the present invention is illustratedin FIG. 2. In this detailed view, the trocar 18 is shown to include thecannula 21 with a working channel 26 (extending generally along an axis27), a proximal end 30, and a distal end 32. The valve housing 23 iscoupled to the distal end 32 in coaxial alignment with the cannula 21.

In this embodiment, the valve housing 23 is constructed with acylindrical, vertical wall 34 and a pair of generally annular horizontalwalls 36 and 38. The wall 36 can be disposed generally perpendicular tothe axis 27 with portions defining an exterior opening 41 for instrumentaccess.

In the illustrated embodiment, the wall 38 is generally parallel to thewall 36 and defines an interior opening 43 which communicates with theworking channel (26) of the cannula 21.

A valve assembly 50 is illustrated within the valve housing 23 but couldbe disposed anywhere along the axis 27. The valve assembly 50 includes ablock 52 of gel material 54. In this embodiment, the block 50 forms ahousing seal 55 with the vertical wall 34 to prevent the leak ofinsufflation gases between the gel material 54 and the housing 23. Thegel block 52 is further configured with a slit or opening 56 which inthis embodiment extends along the axis 27. This opening 56 is perhapsbest illustrated in the cross sectional views of FIGS. 2A and 2B.

In FIG. 2A, the valve assembly 50 is illustrated in the absence of theinstrument 25 (FIG. 1). Under these circumstances, the gel material 54closes the opening 56 to form a zero seal 58. The zero seal 58 in thisembodiment is formed solely by the gel material 54, generally along theaxis 27, and prevents the escape of insufflation gases through the gelblock 52 in the absence of the instrument 25.

The gel block 52 is not merely a septum having only a thin dimensionalong the axis 27. Rather, the block 52 is preferably formed so that theratio of its thickness to its outermost dimension, such as its radius,is in a range between one and five. The thickness of the block 52 ispreferably in a range between five and ten millimeters. In a preferredembodiment, the gel block 52 in the relaxed state shown in FIG. 2A, hasa thickness of about seven millimeters and an outermost dimension, suchas its radius about 21 millimeters. (In this case the ratio is aboutthree).

Operation of the trocar 18 and associated valve assembly 50 is bestillustrated in FIG. 3. In this case, the instrument 25 is illustrated tobe inserted off-axis through the opening 56. In this view it can be seenthat the portions of the gel material 54 which define the opening 56 ofthe block 52 also form an instrument seal 61 with the instrument 25.This instrument seal 61 prevents the escape of insufflation gasesthrough the gel block 52 when the instrument 25 is present in the trocar18.

FIG. 3 illustrates at least two aspects of the present invention, bothof which relate to properties of the gel block 52 in the presence of theinstrument 25. Initially, it will be noted that the instrument seal (61)will move with the instrument 25. Although the instrument 25 may beinserted along the axis 27, it may also be inserted off-axis or movedoff-axis, as illustrated in FIG. 3, during the operation. Under thesecircumstances, it is important that the instrument seal 61 bemaintained, or permitted to “float” with the off-axis movement of theinstrument 25. The instrument seal 61 is formed by both the instrument25 and the valve assembly 50; however, since the instrument 25 willtypically be rigid, it is up to the valve assembly 50 to accommodatethis flotation.

It is the properties of the gel material 54 which make it particularlydesirable for flotation purposes. Properties of the gel materialincluding elongation greater than 1,000 percent, low durometer, and hightear strength, are fully disclosed in the previously mentionedInternational Application Serial No. PCT/US01/29682.

With the advantages associated with (1) the formation of an instrumentseal and a zero seal with a single valve accommodating a wide range ofdiameters, and (2) the formation of an instrument opening using theinstrument itself, it will be appreciated that the concept of thisinvention will typically be embodied with a structure that isparticularly dependent upon the material which forms the access device18. In a preferred embodiment, the gel material 54 is formed of aKRATON®/oil mixture including a KRATON® tri-block with astyrene-ethylene/butylene-styrene (S-E/B-S) structure in combinationwith a mineral oil. Other tri-block polymers can be used for thisapplication such as styrene-isoprene-styrene, (S-I-S),styrene-butadiene-styrene (S-B-S), styrene-ethylene/propylene-styrene(S-E/P-S) manufactured under the trademark SEPTON® by the Kuraray Co.These general formulas can be further distinguished by the ratio of thestyrene to rubber content: for example, Grade 1650 is a S-E/B-Stri-block with a 29/71 styrene to rubber ratio.

In addition to tri-blocks there are also di-block versions of thesematerials where styrene is present at only one end of the formula, forexample, styrene-ethylene/butylene (S-E/B) di-block.

The various base formulas may also be alloyed with one another toachieve a variety of intermediate properties. For example KRATON® G1701Xis a 70% S-E/B 30% S-E/B-S mixture with an overall styrene to rubberratio of 28/72. It can be appreciated that an almost infinite number ofcombinations, alloys, and styrene to rubber ratios can be formulated,each capable of providing advantages to a particular embodiment of theinvention. These advantages will typically include low durometer, highelongation, and good tear strength.

It is contemplated that the material of the gel block 52 may alsoinclude silicone, soft urethanes and even harder plastics which mightprovide the desired sealing qualities with the addition of a foamingagent. The silicone materials can be of the types currently used forelectronic encapsulation. The harder plastics may include PVC, Isoprene,KRATON® neat, and other KRATON®/oil mixtures. In the KRATON®/oilmixture, for example, oils such as vegetable oils, petroleum oils andsilicone oils might be substituted for the mineral oil. In the broadestsense, all of these mixtures can be described generally as a gel. Thegel will typically have properties including an ability to “flow” whichapproaches that of a fluid. Particularly in the vicinity of any openingor slit 56 extending through the access device 18, propagation of theopening may be of concern. Stresses resulting from the presence of aninstrument will be concentrated at the ends of such an opening or slit.For this reason, a good tear resistance is desired for the gel material.Such a tear resistance is often inherent in the KRATON®/oil mixtures andmay be enhanced by encapsulating the gel in other materials. Forexample, a low tear resistant gel could be encapsulated in a urethanesheath to improve the tear resistant qualities of the resultingproducts. Such a sheath need not be elastic but could be comprised, forexample, of overlapping sheets of a non-elastic material.

Any of the gel materials contemplated could be modified to achievedifferent properties such as enhanced lubricity, appearance, and woundprotection, or to provide anti-cancer or anti-microbial activity.Additives can be incorporated directly into the gel, for example in thecase of pharmaceuticals, or applied as a surface treatment to the gel,for example, to improve lubricity or appearance. Other compounds couldbe added to the gel to modify its physical properties or to assist insubsequent modification of the surface by providing bonding sites or asurface charge. Antioxidants and antirads can be added to the mixture toextend the shelf life of the finished product or increase its ability towithstand radiation sterilization.

Sealing materials used in medical access devices of the past have beenchosen primarily for their durometer and elongation. It is theseproperties which measure the ability of the material to move into smallspaces and crevices as may be required to form an instrument seal acrossthe working channel of a trocar. For example, in the past, a siliconemixture was used in medical valves. This mixture had the followingproperties: an ultimate elongation less than about 1000 percent and adurometer not less than about 5 Shore A.

These properties of the prior art materials are far exceeded by theproperties associated with the present invention which in some respectsprovide a full magnitude of advantage. In fact, the difference betweenthe materials of the prior art and the materials of the presentinvention are sufficiently substantial, that it is perhaps misleading torefer to the present material as merely a gel. According, the materialof the present invention, having properties including an ultimateelongation greater than about 1000 percent and a durometer less thanabout 5 Shore A, will be referred to herein as an “ultragel.”

In a preferred embodiment of the present invention, the ultragelincludes KRATON® and mineral oil and provides a sealing material withthe following properties: an ultimate elongation exceeding about 1500percent, and a durometer of less than about 200 Bloom. The durometer inthis case is considerably lower than that of the prior art materials. Infact, the durometer of the present material is so soft it cannot even bemeasured on the Shore A scale.

The resulting elongation and durometer of the present materialfacilitates its use with as an access valve which is capable of formingseals with a full range of instrument sizes, but is also capable offunctioning as a zero seal. Whereas access devices of the prior art mayhave required as many as six separate seals in order to accommodate afull range of instrument sizes, access devices can now be made with onlya single valve formed of the ultragel material.

In a typical manufacturing process, the KRATON® G1651 is mixed with themineral oil in a ratio by weight of 1 to 9. In order to manufacture thismaterial, the combination is heated to a temperature of about 200°centigrade. In a preferred method of manufacturing, the mold is providedwith a circumferential ring insert which is molded into the gel, andslit inserts which can be removed from the gel to form the opening orslit 56. The resulting gel can be coated with cornstarch to reduce tackand cooled at room temperature.

Many of the properties of the KRATON®/oil mixture will vary withadjustments in the weight ratio of the components. In general, thegreater the percentage of mineral oil, the more fluid the mixture; thegreater the percentage of KRATON®, the more rigid the material. Weightratios of KRATON® to oil as low as 1 to 5 have been contemplated for amore rigid structure. As the KRATON®/oil weight ratio approaches 1 to10, the mixture becomes more liquid. Ratios as high as 1 to 15 have beencontemplated for this invention.

The processing temperature can also vary considerably as it is primarilydependent on the type of KRATON® used. Temperatures in a range of about150° centigrade to about 250° centigrade have been contemplated.

With an appreciation that these ratios and temperatures can developconsiderably different properties, it is now apparent that thesematerials can be layered to provide generally different propertieswithin each layer. For example, an outer layer might be formed of aKRATON®/oil mixture having more rigid properties, thereby providing thegel block 52 with an outer layer that is more rigid. After that layer isat least partially cured, another layer of the material can be pouredinside of the outer layer. This second layer might be softer providingthe gel block 52 with the significant sealing properties. It has beenfound that successive layers will tend to fuse slightly at theirinterface, but will generally maintain their separate identities.Additional layers could be added to provide a progression of propertiesin a particular device.

Another aspect of the invention associated with insertion of theinstrument 25 relates to movement of the gel material 54 as the opening56 is spread by the instrument 25. As this opening 56 enlarges, thedisplaced gel material, which is generally non-compressible, willattempt to expand. In order to accommodate this expansion, it isdesirable to provide air pockets or voids 65 into which the gel material54 can move. These voids 65 are most prominently illustrated in FIG. 2Ain the absence of the instrument 25.

Another embodiment of the invention is illustrated in FIG. 4. In thisembodiment, elements of structure similar to those previously discussedwill be designated with the same reference numeral followed by the lowercase letter “a.” Thus the cannula is designated with the referencenumeral 21 a, the valve housing with the numeral 23 a, and the valveassembly with the number 50 a. In this embodiment, the valve assembly 50a includes a thin septum 70 with the opening 56 a disposed generallyalong the axis 27 a. The septum 70 will typically be formed of anelastomeric material and will be supported within the valve housing 23 aby the gel material 54. In this case, the septum 70 is responsible forthe zero seal 58 a as well as the instrument seal 61 a.

The gel material 54 forms a seal with the septum 70 as well as thehousing seal 55 a with the housing wall 34 a. It will be noted that inthis embodiment, the gel material 54 provides floating support for theseptum 27. Any outward expansion required of the gel material can beaccommodated by the voids 65 a between the gel material 54 and thehorizontal walls 36 a and 38 a.

A further embodiment of the invention is illustrated in FIG. 5, whereinelements of structure similar to those previously disclosed aredesignated with the same reference numeral followed by the lower caseletter “b.” The embodiment of FIG. 5 differs from that of FIG. 4primarily in the location of the gel block 52 b. In this case, thehousing seal 55 b is formed around the axis 27 b between the gel block52 and the horizontal walls 36 b and 38 b of the valve housing 23 b. Thevoids 65 b desired for expansion of the gel block 52 b can be locatedbetween the vertical wall 34 b and the gel block 52 b. This embodimentcould include the elastomeric septum 70 b, or might comprise only thegel block 52 b as illustrated in the embodiment of FIG. 2A.

Another embodiment of the invention is illustrated in FIG. 6, whereinelements of structure similar to those previously disclosed aredesignated with the same reference numeral followed by the lower caseletter “c.” In this embodiment, which may include the septum 70 c, theblock 52 c of gel material 54 c forms the housing seal 55 c around theaxis 27 c with each of the housing walls 34 c, 36 c, and 38 c. Theexpansion voids 65 c can be formed as air pockets within the gelmaterial 54 c of the block 52 c. In such an embodiment, the block 52 cis generally compressible, like a sponge, as the gel material 54 c canexpand into the voids 56 c to reduce the volume of the block 52 c. Withthis compressibility, flotation of the valve assembly 50 c, can begreatly increased with respect to the axis 27 c.

In the embodiment of FIG. 7, elements of structure similar to thosepreviously disclosed are designated with a the same reference numeralfollowed by the lower case letter “d.” This embodiment differs fromthose previously disclosed in that the voids 65 d are formed permanentlywithin the walls of the housing 23 d. For example, the voids 65 d can beformed in the horizontal wall 36 d to accommodate upward expansion ofthe gel block 52 d, as illustrated by an arrow 67. In this embodiment,the elastomeric septum 70 is insert molded with the gel block 52 d, andthe housing seal 55 is formed between the gel block 52 d and the walls34 d and 38 d.

Having disclosed these particular embodiments, it will be understoodthat many modifications can be made without departing from the spiritand scope of the concept. For example, various sizes of the surgicaldevice are contemplated as well as various types of constructions andmaterials. It will also be apparent that many modifications can be madeto the configuration of parts as well as their interaction. For thesereasons, the above description should not be construed as limiting theinvention, but should be interpreted as merely exemplary of preferredembodiments. Those skilled in the art will envision other modificationswithin the scope and spirit of the present invention as defined by thefollowing claims.

What is claimed is:
 1. A surgical access device comprising: a valvehousing; a valve assembly comprising: gel material disposed in the valvehousing, the gel material defining a housing seal with the valve housingpreventing insufflation gas flow therethrough; and a septum valvedisposed between the gel material and the valve housing and positionedwithin an opening extending through the gel material, the septum valvearranged to seal against an outer surface of an instrument when theinstrument is inserted through the septum valve and to float toaccommodate instruments inserted off-axis or instruments moved off-axis.2. The device of claim 1 wherein the valve housing further comprises anupper wall covering portions of the gel material.
 3. The device of claim2 wherein the upper wall is perpendicular to an inside wall of the valvehousing and extending over a portion of the gel material.
 4. The deviceof claim 3 wherein the gel material contacts the inside wall.
 5. Thedevice of claim 2 wherein the upper wall has at least one void.
 6. Thedevice of claim 2 wherein the upper wall has an opening extendingtherethrough, the opening in the upper wall aligned with an opening inthe septum valve.
 7. The device of claim 2 wherein the upper wall has atleast one void positioned on either side of the opening in the upperwall.
 8. The device of claim 2 wherein the gel material contacts theupper wall.
 9. The device of claim 8 wherein the valve housing furthercomprises a lower wall opposing the upper wall and the gel materialcontacts the lower wall.
 10. The device of claim 2 further comprises anelongate cannula extending from the valve housing.
 11. The device ofclaim 10 wherein the valve housing further comprises a lower wallopposing the upper wall and contacting the elongate cannula.
 12. Thedevice of claim 11 wherein the valve housing further comprises an insidewall perpendicular to the upper and lower wall.
 13. The device of claim12 wherein the gel material contacts one of the upper, lower or insidewall of the valve housing.
 14. The device of claim 1 wherein the gelmaterial is non-compressible.
 15. The device of claim 1 wherein thethickness of the gel material is greater than a thickness of the septumvalve.
 16. The device of claim 1 wherein the septum valve is made of amaterial different from the gel material.
 17. The device of claim 1wherein the gel material comprises a di-block or tri-block co-polymerand an oil.
 18. The device of claim 1 wherein the gel material issmaller in width than the septum valve.